1. Technical Field
The present invention relates generally to cutting devices and particularly concerns a device for accurately removing preselected lengths and thicknesses of insulation from electrical wires and the like.
2. Discussion
Many industrial electrical wiring applications utilize long lengths of electrical conducting wire or cable. These wires or cables typically have a center conductor wire, often composed of some conductive metal or alloy such as copper or aluminum. The center conductor wire is typically enshrouded by a thin layer of nylon or similar protective coating, which aids in electrical insulation of the center conductor wire, as well as protection from the elements exterior to the cable. The center conductor and nylon coating are typically enshrouded by at least one layer of insulation. This insulation is often a flexible material, such as silicone rubber, so as to facilitate bending of the wire as well as adaptation of the wire ends to suit the particular need. The adaptation of the wire ends to suit a particular need often requires that certain lengths and thicknesses of the insulation surrounding the center conductor wire be removed for subsequent connection of the center conductor wire or the attachment of an external connector to the center conductor wire.
It is often necessary for safety reasons that insulation be removed to a specific length along a particular end of the cable. By ensuring that only the required length of the center conductor wire is exposed for connection or attachment purposes, the potential for unwanted contact between the center conductor wire and the external environment is avoided. Contact between the center conductor wire and the external environment is undesirable because of the possibility of transfer of electrical energy from the center conductor wire to an external object or human being, and also because of the possibility of the introduction of moisture or foreign material to the center conductor, which can cause premature degradation, corrosion or interference with an electrical connection.
Different applications may require different thicknesses of insulation to be removed from the ends of an electrical cable, such as for alternate connector selections. In addition, some applications of electrical cable may require a stepwise removal of progressively smaller thicknesses of insulation from ends of certain cables. It is important in these applications that the proper thicknesses and lengths be removed for proper fitting and attachment of connectors and other accessories near or at the cable ends, to prevent degradation or destruction of the insulation by stretching or overtightening to compensate for a poor fitting or attachment connection.
Therefore, the proper removal of insulation from electrical wire requires not only a proper length to be removed according to the particular need, but also requires that the one or more layers of insulation present be cut to the proper depth. The depth for cutting insulation from an electrical wire is especially critical because while it is essential to achieve a cut deep enough to pierce through the insulation material entirely, or through a particular insulation layer entirely, it is necessary that the center conductor wire or the thin nylon or other layer surrounding it not be nicked or damaged in any way. Damage to the center conductor wire or the thin nylon or other layer surrounding it causes a danger of improper electrical connections and/or electrical arcing, as well as resistance heating within the wire. These conditions can pose a fire hazard and as such, should be avoided.
Similarly, many types of electrical wire have more than one layer of insulation which must be cut successively at different locations along the length of the wire for certain applications. It is necessary in these situations to cut each successive layer of insulation to a specific desired depth, for removing an outer layer of insulation, while leaving the next inward layer of insulation intact, without any damage to its external surface.
Previous methods for removing insulation from electrical wire have involved the use of hand cutting tools such as Exacto knives. The use of these cutting tools has presented several disadvantages. Cutting insulation by hand has resulted in inaccuracies and inconsistencies in the dimensions of the cuttings made, including improper depth of cutting, which causes either an incomplete cut or a damaging of the center conductor or the nylon or other layer surrounding it. Additional inaccuracies and inconsistencies involve failures in the location of the cut along the length of the wire, as well as the failure to achieve a substantially accurate circumferential cut of insulation around the cable. Overall, the cutting of electrical wire insulation by hand tends to be time consuming as well as laden with errors which must be corrected by repeating the cutting sequence on a new section of wire and involves a waste of materials.
The need therefore exists for an improved method and apparatus for trimming one or more layers of insulation in varying thicknesses and lengths from coaxial and other types of electrical wires and cables.